Comparative Proteomics of Extended-Spectrum Cephalosporin-Resistant Neisseria gonorrhoeae Isolates Demonstrates Altered Protein Synthesis, Metabolism, Substance Transport, and Membrane Permeability.

Nannan Diao,Yang Yang,Guoquan Yan,Yuan Dong,Weiming Gu,Ying Wang

doi:10.3389/fmicb.2020.00169

Abstract

Neisseria gonorrhoeae isolates exhibit resistance to extended-spectrum cephalosporins (ESCs), the last remaining option for first-line empirical monotherapy. Here, we investigated the proteomic profiles of N. gonorrhoeae clinical isolates with ESC-resistance to support exploration of the antimicrobial resistance mechanisms for N. gonorrhoeae. We used comparative iTRAQ quantitative proteomics to investigate differential protein expression of three ESC-resistant N. gonorrhoeae clinical isolates using N. gonorrhoeae ATCC49226 as a reference strain. The expression of 40 proteins was downregulated and expression of 56 proteins was upregulated in all three ESC-resistant N. gonorrhoeae isolates. Proteins with predicted function of translation, ribosomal structure and biogenesis, as well as components of the Type IV secretory systems, were significantly upregulated. Two differentially expressed proteins of ABC transporters were also reported by other teams in proteomics studies of N. gonorrhoeae isolates under antimicrobial stress conditions. Differentially expressed proteins are involved in energy production and metabolism of carbohydrates and amino acids. Our results indicated that amino acid and carbohydrate metabolism, cell membrane structure, interbacterial DNA transfer, and ribosome components might be involved in mediating ESC-resistance in N. gonorrhoeae. These findings facilitate a better understanding of the mechanisms of ESC-resistance in N. gonorrhoeae and provide useful information for identifying novel targets in the development of antimicrobials against N. gonorrhoeae.

Highlights

Gonorrhea, caused by Neisseria gonorrhoeae, has been a major public global health concern (Newman et al, 2015; Unemo et al, 2017, 2019; Wi et al, 2017)
The antimicrobial susceptibility profile of N. gonorrhoeae ATCC49226 has been characterized by others (Nabu et al, 2014, 2017), and we confirmed that it is susceptible to CRO (MIC = 0.015) and CFM (MIC < 0.004)
We found that the expression of six proteins with predicted functions associated with translation, ribosomal structure, and biogenesis was differentially regulated in the three extended-spectrum cephalosporins (ESCs)-resistant N. gonorrhoeae isolates

Summary

Introduction

Gonorrhea, caused by Neisseria gonorrhoeae, has been a major public global health concern (Newman et al, 2015; Unemo et al, 2017, 2019; Wi et al, 2017). Mutations have been associated with N. gonorrhoeae resistance or decreased susceptibility to CRO or CFM, such as mutations in penA, porB, and mtrR genes (Liao et al, 2011; Unemo and Shafer, 2014). Mutations to the mtrR gene or the mtrR promoter sequence causes reduction or loss of MtrR repressive function on efflux pumps (Hagman and Shafer, 1995). This results in enhanced activity of the efflux complex and induces the expulsion of antibiotics from the cell (Golparian et al, 2014). The known resistance factors among gene/protein mutations cannot entirely explain the mechanism of ESC-resistance in N. gonorrhoeae (Ohnishi et al, 2011; Gong et al, 2016)

Results

Discussion

Conclusion